LS-DYNA模拟爆破中时间步长对计算结果影响探讨

Study on Influence of Time Step on Calculation Result in Blasting Simulation with LS-DYNA

为减小LS-DYNA软件模拟工程爆破时产生的误差,探讨了不同输出时间步长Δt对计算结果的影响。通过三个经典算例,数值比较不同时间步长Δt下相应的单元压力、质点速度与加速度的时程曲线的形状与峰值变化规律,并结合实例进行验证。结果表明：Δt值设置越小,绘制出的曲线越平滑,Δt值取1、2或3时的曲线几乎重合;Δt值不为1时,输出的坐标点都包含在Δt值为1的坐标点内;随Δt值增大,结果误差有增大的趋势,但并非严格递增;Δt值等于1时模拟的精确度较高,但求解时间长,且输出数据存储空间大。采用LS-DYNA模拟工程爆破中,Δt值取3-5是比较合理的。

In order to reduce the error in LS-DYNA simulation of engineering blasting, the effect of time step At on calculation results was taken into discussion. Through three typical examples, the curve shape and peak value change rule of the corresponding element pressure, node velocity and acceleration under different At were numerically compared, and were further verified by practical example. The results show that, the smaller At is, the smoother the curve takes on. When At is equal to 1,2 or 3 respectlvely,the curves are almost overlapped. The coordinate points corresponding to the case of △t ≠ 1 are involved in the coordinate points of the △t= 1 case. The error shows an increased trend with increasing At value, but the relation is not a strict increase. A higher accuracy of numerical results can be obtained when △t= 1 except for the longer solution time and larger memory space. It is more reasonable when the value of At ranges from 3 to 5 in the LS-DYNA simulation of engineering blasting.